medwireNews: Pain intensity strongly correlates with disease activity measured by DAS28-ESR in people with rheumatoid arthritis (RA), with the association mostly explained by the patient global assessment (PtGA) element of the composite score, study data show.
Fowzia Ibrahim (King’s College London, UK) and co-investigators believe their findings “strongly support targeting remission and LDA [low disease activity] to minimise pain intensity with the caveat that not all patients with active RA experience substantial pain.”
The researchers explain that although pain management guidelines for inflammatory arthritis underline the need to reduce disease activity in order to minimize pain, it is not fully understood how the two outcomes are related.
To address this, they pooled data from 1132 individuals with RA who participated in five clinical trials and one observational study and were followed up for 12 months. Of these, 490 had early active RA, 469 had established active RA, and 173 had LDA or were in remission.
As reported in Arthritis Research & Therapy, mean pain intensity scores at 12 months, measured using a 100-mm visual analog scale, increased from 13 points among individuals in remission (DAS28-ESR <2.6 points) to 21, 35, and 61 points among those with LDA (DAS28-ESR 2.6 to <3.2 points), moderate disease activity (MDA; DAS28-ESR 3.2–5.1 points), and high disease activity (HDA; DAS28-ESR >5.1 points), respectively.
The team says that the overall correlation between the 12-month pain intensity and DAS28-ESR scores was strong (correlation coefficient [r]=0.64) but notes that pain intensity scores had a broad range within each disease activity category, particularly MDA.
Furthermore, there was wide variation in the strength of correlation between pain intensity scores and individual DAS28-ESR components. The correlation was “strong” with PtGA (r=0.87–0.89), moderate to strong with total joint count (r=0.50–0.65), very weak to moderate with swollen joint count (r=0.14–0.58), and very weak with erythrocyte sedimentation rate (r=0.05–0.10), Ibrahim et al note.
In line with this, they found that, after adjustment for potential confounders, the PtGA explained the majority of variation (76% to 86%) in pain intensity scores and that there was strong agreement between the two measures across all studies.
However, the researchers also observed that “there was some discordance between pain intensity and disease activity across all disease activity levels.”
Specifically, although 81–92% of patients in remission or with LDA had low pain intensity levels (≤34 points), “a considerable number” (7–17%) reported moderate pain (35–74 points), while 45–59% with MDA had low pain intensity and 44–71% with HDA had only moderate pain.
Finally, the investigators report that changes in disease activity scores over time were mirrored by changes in pain intensity. For example, individuals with early and established active RA reported falls in mean pain intensity scores of over 60% from baseline if they achieved LDA, but the reductions were below 35% when MDA or HDA were the outcomes at 6 or 12 months.
Ibrahim et al conclude: “Our results strongly support the EULAR inflammatory arthritis pain management guideline recommendation that the initial crucial step in managing RA pain is controlling disease activity.”
They add: “It therefore seems crucial to focus on reducing disease activity with disease-modifying drugs to control pain before considering additional drug therapies.”
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